Collapsible mold



April 24, 1945. PFLEUMER 2,374,233

COLLAPSIBLE MOLD Filed July 24. 1942 s sheets-sheet 1 z5 Z5 z2 l I I G. I.

i 2;;ORNEY COLLAPS IBLE MOLD Filed July 24, 1942 3 Sheets-Sheet 2 l 45 D I @za 0c l I l o a; Y 2 o.

o m 4 e JZ 54 54 i 67 INVEMOR.

April 24, 1945. H. PFLEUMER coLLAPsIBLE MOLD Filed July 24, 1942 jE:V///////////////////////////mi@/fw l H. )Lw/lill,

INVENTOR atented Apr. 24, 1945 CSIBLE MOLD Hans Pileumer, New Brunswick, N. J., assignor to Rubatex Products, Inc., New York, N. Y., a corporation of Delaware Application July 24, 1942, Serial No. 452,131

7 Claims.

My invention relates to collapsible molds and more particularly to a collapsible frame mold which may be utilized in the manufacture of closed cell cellular expanded rubber.-

In the manufacture of closed cell cellular expanded rubber, various processes may be used, among which is the so-called Chemical Blow method. In this method, a rubber mix is fully masticat'ed and is treated with a chemical, which upon the application of heat, will degenerate to form gases which may expand the rubber.

The( rubber mix thus treated, is then placed in a confining mold and subjected to sufficient heat to cause this degeneration and evolution of gases.

When the presses are opened up after this degenerationV of gases has occurred, the rubber thus blown immediately expands. Simultaneously, the rubber mass is at least partially vulcanized in order to give the same suilicient strength to malntain the closed cellular structure without a bursting of the cells.

This process is described in' application Serial No. 159,706, now U. S. Patent No. 2,299,593, which is assigned to the assignee of the present application. n

Perhaps the most important part of this process is played by the mold Within which the compound is blown. As the process is practiced at the present time, a frame mold is solidly filled with the compound to be blown. The frame containing the rubber is confined between the hot platens of apress and the rubber is blown in this absolute confinement. Consequently, at the time of the blow the pressure developed within the cells is extremely high. Experimental computations reveal that the pressure within the frame, and, therefore, within each cell rises to approximately 68 atmospheres or v1000 pounds per square inch. Before the blown and precured rubber can be expanded, it is necessary to 4cool oi the press and also to cool off the rubber in order to give the rubber enough strength to withstand the stresses to which it is subjected during the removal from the press.

Even-then, the cooled oi rubber, being still under high internal pressure, undergoes violent treatment. Before the press can be opened far enough to make room for. the expanding rubber, the force of th'e internal pressure pushes the rubber through the narrow openings created during the initial separation of theA platens of the press. Even after the press is fully opened, the sharp edges of the mold frame exert a destructive force upon the surface of the rubber sheeting.-

When rubber'is vulcanized in' a confined state and then forcefully expanded into a cellular structure, the cell walls have a tendency to assume the dimensions they had 'during the vulcanization. In other words, there exists a certain powerv`(or memory) in the llm to contract to its original size which is opposed by the internal gas pressure which, as the cells shrink,

grows higher and thereby tends to diiuse through the cell walls.

This phenomenon is more pronounced in expanded rubber which has been expanded from a Drecure mold size to its normal size after the rubber has been cooled oil anda certain amount of the initial tensile strength of the rubber has been recovered. If, however, the precured vulcanized rubber is expanded while it is still hot beforefthe presses have cooled, the lm contraction later on is thus avoided.

Accordingly, it is of extrem-e importance that the expansion be permitted to occur while the rubber is Still hot.

The frame mold previously used in `this process has to a great extent impeded any operation which would permit the separation of the platens of the press while the rubber is hot.

If, for instance, it is desired to blow a finished structure to eight times its solid rubber volume, it may only expand six'times after being expanded cold, and it must be expanded still more in the finishing mold to iill the same out. By doing this, some of the gas content diifuses through the rubber before the matrix is completely filled out, and in case of soft cellular rubber, a flabby and lifeless product results.

In case of hard closed cell cellular rubber, a porous product may result, rather than a closed cellular product. If, however, the rubber is expanded from its precured size while still plastic, the expansion to eight times the original volume may be attained directly without necessitating additional strain upon the cell Walls. In this case, the expanded rubber fills out the secondary mold without voids, the necessary Vulcanizing` heat is transmitted faster and gas within the cells is prevented from diffusing.A

Hot expanding gas has a, greater driving force by approxiamtely 25%, so that when the rubber is expanded while the gas contained in the cells is 'still at elevated temperature, the cells will' be still more elongated, ,or so to speak, overstretched.

Indeed-it has been observed that hot expanded rubber immediately after release, swells up in excess of thevolume intended, whereupon it slowly settles down. is not because the gas es- I have evolved a mold in which the existing difficulties of expansion, marring an otherwise satisfactory process, are overcome.

With my novel mold it becomes unnecessary to cool off the press and the rubber, but the rubber may be expanded While it is still hot without damage being inflicted upon it by the mold.

The essential principle of my mold consists of the feature of interlocking the members of the mold in such a way that they perform as a substantial confining device when the platen pressure is in force, but collapse and separate, when the platen pressure is removed. The members of the frame are thus pushed aside by the expanding rubber and can do vno damage to the surfaces of the rubber sheet.

In other Words, therefore, the. essence of my invention is the provision of a collapsible mold which will form a single solid unitary mold when pressure is applied thereto in a press but which will come apart, when pressure is releasedA so that the expanding material may push the parts of the mold aside during expansion and so that the expanding material will not be marred or distorted by pressure against the portions of the mold itself.

'Il'he principal object of my invention, therefore, is the provision of a collapsible mold for use in treating rubber which is confined between the platens 'of a hot press. v

Another object of my invention is the arrangement of a frame mold in such manner that when external pressure is applied to opposite portions thereof, the frame will act as a single confining mold but when such pressure is released, the portions of the mold will separate so as to permit full expansion of the material contained therein.

These and many other" objects of my invention will become apparent from the following description and drawings, in which Figure 1 is a schematic cross-'sectional view showing an existing type of frame mold for expandilng rubber material partially confined between the platens of a press.

Figure 2 is a cross-sectional view corresponding to that of Figure lwshowing the platensofthe press further opened.

Figure 3 is an end view of a collapsible frame mold of my invention.

Figure 4 is an end view showing the mold of Figure 3 in the condition which it assumes when the platens of the press are opened.

Figure 5 is a view in perspective showing the various parts of my frame mold 4and theirl relationship to each other.

Figure 6 is a view corresponding to that of Figure 5 showing the parts of my frame mold secured to each other.

Referring now to Figure 1, there is here shown somewhat schematically an old type solid frame mold and the condition which occurs where after the rubber has been chemically blown the platens of the press begin to separate.

It will be seen that when the platens 20 and 2l begin to separate the rubber mass 22 which is under a high pressure of the order of 68 atmospheres .or 1000 pounds per square inch within the frame mold 23 begins to splay out around the edges of the frame mold. This obviously results in injury to the rubber sheet when it is fully expanded since the corners 25, 25 tend to cut into the rubber mass as its internal pressure drives it against these corners. Even when the platens of the press are fully expanded, as shown in Figure 2, the same condition occurs since a portion of the rubber mass 22 is still confined within the frame mold 23 while the remainder may splay out. It is not until the rubber mass 22 has been completely removed from the frame mold 23 that itis removed from these cutting or tearing stresses.

Consequently, the rubber sheet produced by the utilization of ,this mold has been tortured, twisted, cut and marred during the process of opening up of the press. In order to avoid this result, at least Ato some extent, it has been found necessary to cool the presses to a great extent before opening the same permitting the rubber to expand. AThis results in a rather limited expansion which thereafter requires a further application of heat to fully expand the rubber.

My invention contemplates the use of a colwill be obviated.

One f'orm lwhich my collapsible mold may take' is shown in Figures 3 to 8 inclusive. I

Referring more specifically to Figure 5, the collapsible mold consists lof a pair of longitudinal members 30 and 3l and a pair of lateral members 32 and 33. The longitudinalmembers 30 and 3| are each notched or recessed at 34, 34 adjacent the ends thereof to receive the ends of the lateral members 32, 32 as seen in Figure 5. A pair of retaining plates 36 and 31 are provided for the upper and lower sides of the frame mold. The functioin of these plates is to maintain the lateral and longitudinal frame portions 30 to 33 in engagement with each other.

It will be seen that, ordinarily, when the members are in the position shown in Figure 5, the

. force of the expanding rubber will drive them directions against the frame mold of Figure 5,

spread apart the longitudinal frame members 30 and 3l. When these members are spread apart slightly, the'notches 34, 34 are disengagedfrom the ends of the lateral frame members 32, 32 and these members may then be spread apart by the expanding rubber mix.

Thus, the cutting or marring of the expanding rubber ,is obviated since the' frame members which would normally perform such cutting, marring or twisting of the expanding rubber are so arranged that they may be pushed aside by the rubber as it expands.

It is necessary in the utilization of a. collapsible or separable frame mold such as that shown in the frame in mold arrangement both preparatoryto placement of the mold in the fnress and while it is in the press. l

The plates 36 and 31 cooperating with the pins and springs in the frame members perform this function. l

Referring now to both Figures 4 and 5, it should be noted that in Figure 4, the longitudinal frame member 3i) of Figure 5 is clearly visible. 'Ihis longitudinal frame member is Iprovided with a plurality of pins 39 extending from the lower side thereof and a similar set of pins @Il extending from the upper side thereof. These pins -are secured to and made a part of the frame member in' any suitable manner.

One way in which these members .may be secured to the frame member 30 is shown, for instance, in Figure '7 where it will be seen that the pins 39 and 40 constitute opposite ends of single dowel pins which are securely positioned in openings in the'longitudinal frame member 3i). Each of the frame members3l to 33 have similar pins extending from either side thereof.

The retaining plates St and 31 each havea plurality of perforations l2 therein which are adapted to register and be engaged by the pins i and se. Thus, when the collapsible mold or frame is laid together in the form shown in Figure 5, the placement of the plates 36 and 31 over, respectively, the pins dt and 39 on either side o f the frame serves to integrate the frame and interengage its parts so that they cannot separate while the plates are in the position of, for instance, plate 31 of Figure 5 or of the plates 36 and ,31 of Figures?, to 8.

Means must be `provided, however, in order to g separate the plates 3S and 31 in order to disengage the perforations i2 thereof from the pins 39 and at so as to permit the frame members to be forced` apart by the expanding rubber. l

For this purpose a plurality of springs 5nd,v 5@ (Figures itc B inclusive) are provided. 'As is seen more particularly in Figure '7, each of the springs 5t is positioned in counter-'sunk openings 5i, si in the :frame members. Thus, for instance, spring sida in the longitudinal member 3G (Figure 7) is secured in opening Slajand is irxnly attachedto the material of theframemember 33 at the bottom 52a of the opening Bla. This holding the frame members 30 to 33 together and the expanded rubber under pressure within the frame moldl will push these frame members apart.

In actual practice, I rst arrange the frame members 30 to 33 in the arrangement shown in Figure 5 whereinthe ends of the lateral members 32 and 33 'are engaged in the notches 34 of the longitudinal frame members 30 and 3l. I then push the plates 36 and 31 down over the ends of the pins and 39 in order that the perforations 4 2, 42 of the plates may be engaged by the pins and thus hold the frame member in place.

I then pass the bolts Gt having thewinged heads 6i through the openings 52, 62 in each of the plates into corresponding threaded openings '63, 63 in each of the frame members andby tightening these bolts securely compress the springs v and rmly hold the plates 36 and 31 in place as shown in Figures 6 to 8. Thereafter, I place the U-,shaped clamps 10, 10 over the edges of the composite frame member. these clamps being sufiicient to hold the frame in molding arrangement. Of course, it will be.

understood that the rubber mix which is to be chemically blown and expanded is now inside the frame mold of Figures 6 to 8. The mold may now be left in this condition until the operator is ready to place the same between the platens of the press.

When this operation is to be performed, ,the

f bolts Gli are removed by rotating the winged head 8| thereof and the only force now holding the plates 36 and 31m place on the frame mold and thus holding the mold in molding position are the clamps 1B. l

The platens of the press are nowfully separated and the formed mold with the bolts removed but the clamps holding the same together is placed between these platens. The platens are then brought together to a point where the space between the platens is only slightly wider than the U-shaped clamps 1i). The U-shaped clamps 1t are then removed. The springs 50 will now be permitted to expand to force the plates 36 and 31 against the platens but the space through which 1 the-plates 36 and 31 may then be moved is now so spring when ruily extended extends substantially tended will extend beyond the bottom of the.

frame member 3d.' As will be seen from Figures 5 and 7, two such spring' members are provided at either end of the longitudinal frame member 3@ on either side thereof.

Similarly, springs 5ta, Etc are provided for the lateral frame member 33 and springs 50d, 50d are provided for the lateral frame member 32; and a similar set of springs is `also provided for the longitudinal frame member 3L'. A n

Accordingly, when the plates 36 and 31 are pushed down over their respective pins38 and tt so that the perforations 42 thereof engagewith l the pins, the various springs S'on either side are compressed so that when the pins holding the l Jplates 36 and 31 against the frame mold are released, the springs will `push the plates away and disengage the pins froml the perforations.

Upon the occurrence of this disengagement',-

there will no longer be any structural element small, that this movement of the plates will not disengage the' perforations 42 thereof from the pins 39 and 8|).

The platens are now brought tightly together, v

thus forcing the plates 36 and 31 against the frame mold so that the form which the mold now assumes withinA the press is that shown in Figure '1 with, however, the bolts '60 having the winged head 6I and the clamps 10 removed.

The blowing or expanding operation now takes place. Upon completion of this blowing or exl pending operation, the platens 20, 2i of the press (Figure 4) may now be separated. As this separation occurs. the springs 50 as previously described andas is seen in Figure 4. push the plates 3 and 31 away from the frame members 30 to`33 until the pins 39 and 40 are disengaged from the perforations 42l therein. Immediately upon the occurrence of this disengagement, the blown rubber in the mold is now permitted -in its expansion to push the frame members apart-'rst'by pushing the longitudinal members 30 and 3| outwardly until the notches 34 are disengaged-from the lateral frame members 32 and 33 and then by pushing all of the frame members outwardly.

'Figure 4 represents but an instantaneous stage in this process whichshows the condition where the platens 20 and 2i of the press have been separated suiciently to permit-the plates 36 and 31 to be pushed out of engaging relation with the frame members expanding rubber has begun to drive the frame 30 t0 33. At this instant, 'the members apart and as it expands drives these I members apart in the manner previously pointed out.

of this type, the diiculties encountered with the previous solid frame molds and described more particularly in connection with Figures 1 and 2 ,are obviated. The rubber is not cut, marred or twisted during the separation of the platens of the press. Since the rubber may now freely ex- 'pand without being cut against the edges of the frame mold, it is not necessary to cool the rubber before separating the press, but the press may be separated while it is hot. This also adds to the efficiency of the operation since it is not then necessary to cool the entire press but rather the press may be used again for a subsequent operation without having to be brought up to the appropriate heat once more, yff

-In Figures 9 to 11 I have shown a modication 4of my device which, however, does not require the utilization of the platesA 33 and 31; which, in

fact, does not require the utilization of the pins' or springs previously described. Here again, the

4longitudinal frame members |30 and |3| arenotched at |34 in order to receive the ends of the lateral frame members |32 and |33. In this case it should be noted the frame members |30 to |33 are so arranged as to form a substantially rectangular figure, where, however, the corners extend slightly outwardly.A This shape thus .im-

parted to the mold is Vimportant for purposes of future expansion.

By the utilization of4 a collapsible frame mold in position, as shown in Figure 10, the frame ymembers cannot separate. When the locking members |40 and |4| are pushed to the position shown in Figure 11, then the longitudinal frame member is no longer retained in position by these members' may now y apart under the pres' sure of the expanding rubber.v Accordingly, the mold may readily collapse in the manner pre-.- viously described.

Although it is not essential, various mechanical aids may be provided to assist these members inA iiying apart under the influenc'eofa the blown rubber once the locking-members and |4| are disengaged. Thus, for instance, I may provide' springs |60, |60 secured lat the bases |62 ofxcountersunk recesses |6| in each of the ends of'thelateral frame members |32 and |33. when Where a square sheet of closedcell-cellular expanded rubber is desired, the rubber sheet in the precure 'stage must be so'i'ormed that it may readily fill out the final mold. When, in the precure stage, the rubber is formed in exact rectangular form, then when it has been placed in the final mold, the corners tend not to ll out the mold. This is so because the expansion diagonally must be over a greater extent than the expansion along -lines bisecting the center of the sides of the rectangle. Accordingly, if in the pre. cure stage, the corners of the rectangle of rubber are extended outwardly to a slight extent, this disadvantage is overcome and i'n the final curing stage, the sheet of rubber may extend to fully illl out the rectangular mold. f A 'I'his shape of the frame mold may lbe utilized not only in the construction of Figures 9to 1l but also in the construction of Figures. 3 to 8. It may, in fact, be utilized in connection with solid frame molds where it may be found necessary or desirable to use such molds. The frame members 30 to |33' are held to,- gether by lateral locking members |40 and |4|. These members as may readily be seen in Figures 10 and 1l have longitudinal extensions |50, |3| at each end thereof which engage against the outside ends of the longitudinal frame members |30 and |3|. Thus it will be seen from an inspection of Figures l0 and 1l that the lateral frame members |32 and |33 are held in position by their engagement inthe notches |34 of the longitudinal frame members |30A and |3I, while the longitudinal frame members |30 and |3| are held in fixed relationship with each other by the engagement of the extensions |50 and |5| of the members |40 and |4| against their outer ends.`

As long as the locking members |40 and I4| are the frame .members |30 to` l|33 are placed t0- gether, theends' of the springs |60 are pressed against the bases-of the notches |34. The outer ends ofthe springs ||i0 may, if desired, merely bear against the base of the notch- |34. In order,` however, to positively position the frame meinbers with respect to each other, an opening |65 may be provided in the base of .each notch within which the outer ends ofthe springs may register.

On release of any force which holds these frame Amembers together. the extensions of the springs |50 will drive the frame members apartvso that an additional mechanical bias in addition tothe fpressure of the blown orexpanded rubber lwill act to separate the frame members. The lateral frame members |32 and |33 will begin to move outwardly as soon-as their ends are disengaged from the ends |34. However, the springs will still be in the notches atthis time so that the expanding force ofthe Ablown rubber will tend to In order to obviate this result, a slot |10 may be placed in the end of each of the longitudinal frame members |30 and |3| communicating with therbase of the notch or the base ofthe spring v retaining openinginthe ends ofthe longitudinal fra-me members |30 and |3| -so that the' springs may slide out through the slots. These slots' are of a width equal in diameter to the spring retaining opening hereinbefore described and thus permit the springs readily to slide out while they do not interfere with the locking effect exerted by the notches 34,

Such spring members may, of course' be secured vin the base of "notches |34 and bear against the ends of the lateral bars, in which case no slots |10 need be provided; or a combination of these elements may be useda spring being secured at the end of a lateral bar on one side and in a notch at 'the other side. b

The engagement of the frame members with each other to form the collapsible framing mold and the arrangement of thelocking members 40 and |4| to hold the collapsible framing mold together presents no diilculties whatever; nor does will be interposed in the path of the expanding A the separation of the members of the mold, provided appropriate precautions are taken.

For this purpose, it should be noted thatthe locking members |60 and |I|| have a height which is substantially less than the height of the frame members |30 to |33. Accordingly, `when the platens 20 and 2| of the press are tightly pressed against the frame members |30 `to |33, the locking members M and MI, since they have awidth which is less than the distance between the platens, are loose so that they may be readily moved to disengagingposition.

However, this disengagement of the bars |80; |4| must be uniform on both sides since othermeans which I have found desirable in practice.

is shown in Figures 10 and 11.

In the exact center of bar |30, `a stud 200 is fastened by thread or welding to form an integral part of this frame bar. Upon this stud 200 the rubber to mar, twist or cut the same.

. Suitable guards maybe provided outsidethe presses to catch the frame "members as they sepa- 'rate or suitable securing members may be provided'to preventthe frame members from moving beyond a predetermined expansion.v

Whenit is desired now to use the mold once more, the members need only be assembled oncemore to the position shown in Figure and the processmay be repeated.

' In each of the foregoing modications, the essential element is the provision of a frame mold 'so arranged that the4 elements thereof may ily 4apart in accordance' with the expansion of the rubber so that a condition suchas that which obspreading assemblyis slidably mounted. It conf sists of a length of pipe 2|| forming on the outside lend a handle 202 and on the insideend the sleeve 20B bearing snugly upon stud 200. Two

clevisedl ears 206v are'l attached at the opposite sides to the pipe 2H toj which by means of clevis pins 209, 2|0, the two 'spreading legs 201|, 200,

The movement of the hooks |50 is short, while the movement of the sleeve is long, so that there is no difnculty in forcing the hooks |50 out-of place. I

The spreading'device may be attached at any l time before the intended disengagement and one device may serve many molds.

' which vsare of the same length are movably setains in connection with the solid frame ,mold- --shown in Figures 1 and 2 will not occur.

lBy the utilization of such a slidable frame mold, the marring, distortion, twisting or cutting ofthe rubber is prevented. Since the rubber may readily expand in. all, directions without being inhibited in any way, it is possible to separate 'the' pla-tens of the press before coolingthe rubber so that a more even expansion of the rubber lis obtained while at' the same time eiliciency in operation is increasedsince beheated up once more. i y

` In vall of the foregoing, I have described my in-- vention only in connection with preferred embodiments thereof. -Many variations and modicationsV should now be obvious to those skilled in the art, I prefer therefore' to be bound not by the specific disclosures herein but only by the appended claims. o

Iclaim:

1'. In combination a frame mold and a press having a pair of platens, said mold being disposable Y between the-platens of the press, said mold comprising a plurality of separable frame members .means for interconnecting said frame members in framing relation; said means cooperating with the .pla.tensv of the press-for connectingA said members As seen in Figure l0, when the mold' has been prepared for use with the locking members and |48 in place thereon, the handle 202 is positionecl outwardly or may be removed.

Links 201 .and 208 also have al height which. is substantially less than that of the frame members 30 to |33 and likewise, the diameter of the sleeve 20 is substantially less than' this height so that the links and-the sleeve may readily. move between the platens of the press when these plat'-,

ens are vtight against the frame members.

" and operable upon the separation of the platens of the press to eiect disconnection of said mem- 2.. In combination a frame .mold and a. press A having a o f platens, said mold being disposable between the platens of the press, said mold comprising a pluralltyof separable frame members; means for interconnecting the ends of said frame members in framing relation; saidmeans.

cooperating with the platens of the press for connecting said members and operable upon the seperation of the platens of the press connection of saidzmembers.

The frame mold in the condition as shownv in Figure 10 is now placed onI the lower platenZ (where it may be placed Without the spreading device), the rubber mix'is placed therein and the upper platen 20 is pressed down tight against the frame mold and heat is applied to cause the blow and expansion.

When the spreading device is put in operation,

then by simply pushing the handle against the frame, the locking bars |40 andl IM are moved out of position, and the frame 'may then beopened bythe expanding rubber when the platens of the press are separated. l

Now immediately upon separation of the platens 20 and 2| of the press, the frame members |30 to |33 will be pushed apart by the springs |60 and by the expansion of the blown rubber, kso that no cutting edge or stiilly positioned member .3. In combination a frame mol-d and' alpress' having a pair of platens, said mold being'disposable between the platensv ofthe press, said mold comprising four separable frame members;means for interconnecting the ends of said frame membersin substantially rectangular framingrelation; said means cooperating with the platens of the press for connectingsaid lmembers and'operable upon the Lseparation of the platens of the press to effect disconnectionof saidz members.

' 4. In' combination a frame mold and a press having a lpair ofplatens, said mold being disposable between the platens of the press,A in a. process of expanding material within a, confined area;

said moldA comprising a plurality-of separable trame members arrangeablein framing relation to -iorm a coniining frame for said material, each of' said members -a plurality of pinsfex- .tending therefrom'normal tothe plane of -said -theplatens need not rangeable in framing relation to form a conning frame. for said material, each o! said members having a plurality of pins extending therefrom normal to the plane of said frame; a pair of ing a plurality oi' separable frame members ar- 10 plates,'-each plate having a plurality of perfora- 15 tions registrable with said pins and disposablev on either side of said-` frame; said plates when in place upon said pins and when said mold is coniined between said platens of the press maintaining said members in framing relation, and spring 20 means interposed between said members and said plate urging said plate away from said members; the bias of said spring means being counteracted by the pressure of the platens of said press when said mold is in said press. 25 6. A frame mold for use between a pair of j platens of a press in a process dfexpanding material within a conned area; said mold comprising a plurality of separable iramevmembersarrangeable in framing relation to form a confining frame for said material, each of said members having a plurality of pins extending therefrom" normal to the plane of said frame: a pair of plates, each platehaving a plurality of perforations registrable with said pins and disposable on either side of said frame; said plates when in place upon said pins and when said mold is connned between said platens oi the press maintaining said members in framing relation; spring means interposed between said members and said plates urging said plates away from said members; the

.bias of said spring means beingcounteracted by the pressure of the platens of said press when said mold is in said press; and means for count`eract ing the bias oi' said spring means prior to the placement of said mold in said press.

7. A frame mold for use between a pair of platens of a press in a process of expanding material within a conned area; said mold comprising a plurality of separable frame members ar rangeable in framing relation w form a conilning frame for said material, each of said members having plurality of pins extending therefrom normal to the plane of said framef a pair of plates. each plate having a plurality of periorations registrable with said pins and disposable on either side of said-frame; said plates when in placeupon said pins and when said mold is confined between said platens of the press maintaining said members in framing relation, and spring means interposed between said members and saidplates urg- HANS PFLEUMER. 

